O comando tzutil.exe está disponível no Windows 7/2008
TZUTIL </? | /g | /s TimeZoneID[_dstoff] | /l>
Parameters:
/? Displays usage information.
/g Displays the current time zone ID.
/s TimeZoneID[_dstoff]
Sets the current time zone using the specified time zone ID.
The _dstoff suffix disables Daylight Saving Time adjustments
for the time zone (where applicable).
/l Lists all valid time zone IDs and display names. The output will
be:
<display name>
<time zone ID>
Examples:
TZUTIL /g
TZUTIL /s "Pacific Standard Time"
TZUTIL /s "Pacific Standard Time_dstoff"
Para definir como UTC, use um comando como TZUTIL /s "UTC"
.